Support for solar energy collectors

ABSTRACT

A solar energy collection system can include support devices made with bearings formed from sheet material. These bearings can be optionally formed so as to provide tool-less connections to their associated bearing housings. The bearings can be formed with an open configuration allowing a shaft to be inserted into an open bite of the bearing. Optionally, the bearing can be made from an ultrahigh molecular weight polyethylene plastic material. Additionally, two open-type bearing assemblies can be mounted axially offset and opposed to one another.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally tosolar energy systems which include supports for solar energy collectingdevices.

BACKGROUND

Larger solar collector installations usually include an array of solarcollector devices. Such systems can be used in conjunction withphotovoltaic modules, thermal solar collector devices as well asconcentrators for concentrating solar energy onto photovoltaic devicesor thermal solar collection devices.

Some of these solar collector installations include hardware forautomatically adjusting the position of the collector devices to trackthe sun as it moves across the sky. This tracking movement can beaccomplished in a number of different ways. Some systems use a singleaxis tracking system in which the collector devices pivot about a singleaxis. Such single axis type tracking systems often include a drive shaftor “torque tube” which defines a single pivot axis.

Further, in some of these systems, the torque tube can be used to bothsupport the solar collector devices and transmit the torque used foradjusting the position of the solar collecting devices. In order toreduce friction which would resist the pivoting movement of the torquetube, some systems include bearings for supporting the torque tube abovethe ground and so as to be pivotable about the pivot axis.

Because the torque tubes pivot through a limited range of rotation aboutthe axis, conventional roller bearings are not necessary for suchapplications. Rather, roller bearings would present an unnecessarilylarge expense. Thus, some sun tracking solar systems include other typesof bearings.

BRIEF SUMMARY

An aspect of at least one of the inventions disclosed herein includesthe realization that costs for constructing sun tracking solarcollection systems can be reduced by using bearings that are lower costand less mechanically complex than a conventional roller bearing. Forexample, some solar systems are designed to pivot the solar collectiondevices over a range of motion of only about 30-60° for each siderelative to a vertical alignment. Additionally, in some designs, thebearing supports for the torque tubes can be disposed between mounts ofother devices that are connected directly to the torque tube. Suchdevices would normally would interfere with the installation of atypical roller bearing installation. Thus, a bearing that can be matedwith a torque tube at a position between other components connected toit, such as mounts for solar collector devices that may be preinstalledat a factory, can help reduce the labor required for installing suchsolar systems.

Thus, in accordance with at least one of the embodiments disclosedherein, a sun-tracking photovoltaic solar collector array can compriseplurality of photovoltaic devices. A support assembly can support thephotovoltaic devices so as to be pivotable about a pivot axis. Thesupport assembly can comprise at least a first pivot supporting theplurality of photovoltaic modules, at least a first bearing supportingthe first pivot so as to be pivotable about the pivot axis, and at leastone pier supporting the bearing at a position above a support surface.The bearing can comprise at least a first reduced friction memberextending around a first arc of at least about 100 degrees about thefirst pivot, the first reduced friction member comprising a first end, asecond end, and a central portion, the first and second ends beingspaced apart sufficiently to allow at least a portion of the first pivotto pass between the first and second ends.

In accordance with another embodiment, a method of assembling asun-tracking photovoltaic solar collector array can comprise mounting afirst bearing housing at a position above the ground, inserting a firstbearing member into the first bearing housing such that the firstbearing member sags downwardly with first and second terminal ends ofthe first bearing member are spaced apart thereby having an upwardlyfacing bite, and lowering a torque tube such that a portion of thetorque tube passes between the first and second terminal ends of thefirst bearing member and onto the bite of the first bearing member. Thefirst bearing member can provide reduced friction with an outer surfaceof the torque tube such that the torque tube can pivot relative to thefirst bearing member, where the torque tube supports a plurality ofphotovoltaic devices.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a schematic top plan view of a solar collector systemaccordance with an embodiment;

FIG. 2 is a schematic diagram of the system illustrated in FIG. 1illustrating optional electrical connections of the collector systemwith various electrical components;

FIG. 3 is a perspective view of the solar collection system of FIG. 1,and illustrating a tracking drive system, a plurality of piles mountedto the ground and supporting a plurality of torque tubes with aplurality of bearing assemblies, in accordance with an embodiment;

FIG. 4 is a schematic side elevational view of a concentratedphotovoltaic sun tracking assembly in which the bearing assemblies ofFIG. 3 can also be used;

FIG. 5 is a perspective view of an embodiment of the bearing assemblyillustrated in FIG. 3 supported by an optional design for a pile;

FIG. 6 is an exploded view of the bearing assembly illustrated in FIG.5;

FIG. 7 is an enlarged perspective view of a bearing member of theassembly illustrated in FIG. 6;

FIG. 8 is an enlarged perspective view of a bearing housing of thebearing assembly illustrated in FIG. 6;

FIG. 9 is a front elevational view of the bearing housing illustrated inFIG. 8;

FIG. 10 is a perspective view of another embodiment of the bearingassembly supported by a pier;

FIG. 11 is an exploded view of the bearing assembly illustrated in FIG.10;

FIG. 12 is a side elevational view of the bearing housing illustrated inFIG. 11;

FIG. 13 is a front elevational view of the bearing assembly illustratedin FIG. 10 with the bearing member installed therein;

FIG. 14 is a perspective exploded view of another embodiment of thebearing assembly having a lower portion and an opposed, axially offset,upper portion;

FIG. 15 is a side elevational view of the bearing assembly of FIG. 14;

FIG. 16 is a perspective view of yet another embodiment of the bearingassembly having a two-part housing and a safety strap;

FIG. 17 is an exploded perspective view of the embodiment of FIG. 16;

FIG. 18 is an enlarged perspective view of one part of the two-parthousing illustrated in FIGS. 16 and 17;

FIG. 19 is a front elevational view of the bearing assembly of FIG. 16with the safety strap removed;

FIG. 20 is a side elevational view of the part of the housingillustrated in FIG. 18.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the proceeding technical field, background,brief summary, or the following detailed description.

“Coupled”—The following description refers to elements or nodes orfeatures being “coupled” together. As used herein, unless expresslystated otherwise, “coupled” means that one element/node/feature isdirectly or indirectly joined to (or directly or indirectly communicateswith) another element/node/feature.

“Inhibit”—As used herein, inhibit is used to describe a reducing orminimizing effect. When a component or feature is described asinhibiting an action, motion, or condition it may completely prevent theresult or outcome or future state completely. Additionally, “inhibit”can also refer to a reduction or lessening of the outcome, performance,and/or effect which might otherwise occur. Accordingly, when acomponent, element, or feature is referred to as inhibiting a result orstate, it need not completely prevent or eliminate the result or state.

“Tool-less connection”—The following description refers to devices orfeatures being connected with “tool-less connections”. As used herein,unless expressly stated otherwise, “tool-less connection” means that oneelement/node/feature is directly or indirectly joined to (or directly orindirectly communicates with) another element/node/feature with amechanism that can be operated by a human without any tools or otherseparate parts to achieve a joined state and optionally to bedisconnected from the joined state.

In addition, certain terminology may also be used in the followingdescription for the purpose of reference only, and thus are not intendedto be limiting. For example, terms such as “upper”, “lower”, “above”,and “below” refer to directions in the drawings to which reference ismade. Terms such as “front”, “back”, “rear”, and “side” describe theorientation and/or location of portions of the component within aconsistent but arbitrary frame of reference which is made clear byreference to the text and the associated drawings describing thecomponent under discussion. Such terminology may include the wordsspecifically mentioned above, derivatives thereof, and words of similarimport. Similarly, the terms “first”, “second”, and other such numericalterms referring to structures do not imply a sequence or order unlessclearly indicated by the context.

The inventions disclosed herein are described in the context ofphotovoltaic arrays and modules. However, these inventions can be usedin other contexts as well, such as concentrated PV systems, thermalsolar systems, etc.

In the description set forth below, a solar energy collection system 10is described in the context of being formed by a plurality of solarcollection modules, supported so as to be pivotally adjustable forsun-tracking purposes. Each of the modules can include a support membersupporting a plurality of solar collection devices as well as wiring forconnecting the various solar collection devices to each other and toother modules. The system 10 can also include devices for reducinglabor, hardware, or other costs associated with installing such asystem. For example, the collection system or the modules included insuch a system can be supported above the ground with bearing assembliesthat include one or more various features designed to reduce the cost ofthe manufacture of such bearings and simplify the installation ofrelated components at an installation site.

FIG. 1 illustrates the solar collection system 10 including a solarcollector array 11 which includes a plurality of solar collectionmodules 12. Each of the solar collection modules 12 can include aplurality of solar collecting devices 14 supported by a drive shaft ortorque tube 16. Each of the torque tubes 16 are supported above theground by a support assembly 18. Each of the support assemblies 18 caninclude a pile and a bearing assembly 20, described in greater detailbelow with reference to FIGS. 5-18.

With continued reference to FIG. 1, the system 10 can also include atracking drive 30 connected to the torque tube 16 and configured topivot the torque tube 16 so as to cause the collector devices 14 totrack the movement of the sun. In the illustrated embodiment, the torquetubes 16 are arranged generally horizontally and the modules 12 areconnected to each other in an end to end arrangement, as more fullydescribed in U.S. patent application Ser. No. 13/176,276, filed Jul. 5,2011, the entire contents of which is hereby expressly incorporated byreference. However, inventions disclosed herein can be used in thecontext of other types of arrangements. For example, the system 10 caninclude a plurality of modules 12 that are arranged such that the torquetube 16 is inclined relative to horizontal, wherein the torque tubes 16are not connected in an end to end fashion, such as the arrangementillustrated and disclosed in U.S. Patent Publication No. 2008/0245360.In that context of the use, the bearing assemblies 20 can be used inplace of the bearings identified by the reference 40 in FIG. 6 anddescribed in paragraph [0033] as well as bearings identified by thereference 72 in FIG. 8 and described in paragraph [0037] of the2008/0245360 patent publication. The entire contents of the 2008/0245360patent publication is hereby expressly incorporated by referenceincluding the illustrations and the descriptions of the bearings 40 and72.

In embodiments where the torque tubes 16 are arranged horizontally andthe modules 12 are connected in an end to end fashion, the bearingassemblies 20 can be used in place of the bearings mounted on top ofsupports 16 in FIG. 2 of U.S. Patent Publication No. 2010/0139646.Further, the drive system 30 can be constructed and operated in themanner disclosed with regard to the tilt assembly 50 of U.S. PatentPublication No. 2010/0139646. The entire contents of U.S. PatentPublication No. 2010/0139646 is hereby expressly incorporated byreference.

Additionally, the solar collection devices 14 can be in the form ofphotovoltaic panels, thermal solar collection devices, concentratedphotovoltaic devices, or concentrated thermal solar collection devices.In the illustrated embodiment, the solar collection devices 14 are inthe form of photovoltaic panels.

With reference to FIG. 2, solar collection system 10 can further includean electrical system 40 connected to the array 11. For example, theelectrical system 40 can include the array 11 as a power sourceconnected to a remote connection device 42 with power lines 44. Theelectrical system 40 can also include a utility power source, a meter,an electrical panel with a main disconnect, a junction, electricalloads, and/or an inverter with the utility power source monitor. Theelectrical system 40 can be configured and can operate in accordancewith the descriptions set forth in U.S. Patent Publication No.2010/0071744, the entire contents of which is hereby expresslyincorporated by reference.

FIG. 3 illustrates the array 11 with all but one of the solar collectiondevices 14 removed. As shown in FIG. 3, each of the support assemblies18 includes the bearing 20 supported at the upper end of a pile 22. Thetorque tube 16 can be of any length and can be formed in one or morepieces. The spacing of the piles 22 relative to one another, can bedetermined based on the desired limits on deflection of the torque tubes16 between the support structures 18, wind loads, and other factors.

The tilt drive 30 can include a drive strut 32 coupled with the torquetube 16 in a way that pivots the torque tube 16 as the drive strut 32 ismoved axially along its length. The drive strut 32 can be connected withthe torque tube 16 with torque arm assemblies 34. In the illustratedembodiment, the torque arm assemblies 34 disposed at an end of each ofthe torque tube 16. Additionally, the array 11 can include an electricalwire tray 60 supported by one or more of the piles 22, or by othermeans.

As noted above, and with reference to FIG. 4, the array 11 can be in theform of a plurality of sun tracking, concentrated photovoltaicarrangements. For example, as shown in FIG. 4, a concentratedphotovoltaic solar assembly 100 can include a pile 102 which supports across beam 104 and a torque tube 16. The cross beam 104 in turn supportsfirst and second groups of concentrated elements 120, 140, supported bythe cross beam 104.

In the illustrated embodiment, one group of concentrated elements 120face in one direction and the second group of concentrated elements 140are positioned so as to face the opposite direction, with the changeoverbetween them occurring at the torque tube 106. The pier 102 can be asingle post or one of several supporting the solar concentrator assembly100.

Connectors 150 support the concentrator elements 120, 140 relative tothe cross beam 104. Additionally, photovoltaic collectors 132, 134, 152,154 can be mounted on the back sides of the concentrator elements 120,140. In this configuration, each of the concentrator elements 120, 140are configured to focus a band of concentrated light onto thephotovoltaic units 132, 134, 152, 154. A sun-tracking drive system candrive the torque tube 16 to pivot about the pivot axis A. Further detailregarding the optional configuration of a concentrated photovoltaicenvironment of use for the bearings 20 is set forth in U.S. patentapplication Ser. No. 12/977,006 filed Dec. 22, 2010, the entire contentsof which is hereby incorporated by reference.

With reference to FIG. 5, the bearings 20 can be supported directly onpiers 102 described above with reference to FIGS. 1-4. Optionally, thebearings 20 can be supported upon an optional bearing support 202.

As shown in FIG. 5, the bearing support 202 can include a lower end 204which can be configured to provide a secure connection to a cylindricalpier, such as the piers 102 illustrated in FIGS. 3 and 4. In suchembodiments, the lower portion 204 includes a plurality of mountingplates 206 configured to extend around an upper end of a cylindricalpier 102. Fasteners (not shown) can be used to attach the plates 206 tothe upper end of a pier 102.

The support 202 also includes an upper end 208. A mounting plate 210 canbe disposed between the lower portion 204 and the upper portion 208. Themounting plate 210 can be securely connected to the plates 206 by anydesired means, such as for example but without limitation, welding.

The upper portion 208 is also connected to the mounting plate 210. Insome embodiments, the upper portion 208 includes a box beamconfiguration formed of four plates 212 connected together to form agenerally vertically extending support structure. However, otherconfigurations can also be used.

The lower end of the upper portion 208 can be further fixed to themounting plate 210 with gussets 214. The upper end of the upper portion208 is secured to the bearing 20.

With reference to FIG. 6, the upper end 220 of the upper portion 208 canbe provided with a shape complementary to a shape of the lower surfaceof the bearing 20. Whether having such a complementary shape or adifferent shape, the upper ends 220 can be fixed to the bearing 20 bywelding or any other method of engagement. Additionally, the upperportion 208 can include an aperture 221 which can be configured toreceive a fastener, such as a bolt, for securing a safety strap 321(FIG. 10).

As shown in FIGS. 6-8, the bearing 20 can include a housing 250 and abearing member 252. In some configurations, optionally, the bearing 20can be configured such that the bearing member 252 rests in the housing250 in such a way that it is essentially “trapped” within the housing250, for example, with a tool-less connection.

With reference to FIG. 7, in some embodiments, the bearing member 252can be made from a sheet material designed to provide reduced frictionwhen sliding against an outer surface of a torque tube 16. As notedabove, the torque tube 16 can be made out of any desired material. Insome embodiments, the torque tube 16 is formed of hot dipped galvanizedsteel. In some embodiments, the bearing 252 can be made from an ultrahigh molecular weight polyethylene (UHMWPE) plastic material. However,other materials can also be used, such as grease soaked cotton, wood,Delrin, Nylon, Polyethylene, Polyurethane, Polytetrafluoroethylene,Brass, Polystyrene, Polyoxymethylene, Acrylonitrile butadiene styrene,Polyamide, or Polyphenylene Oxide.

With continued reference to FIG. 7, in some embodiments, the bearingmember 252 can have a generally rectangular configuration with a firstwidth W1. and can extend longitudinally along a longitudinal axis LA. Inthe illustrated embodiment, the bearing member 252 includes shoulders254 at each end with a protruding portion 256 disposed between theshoulders 254, also at each end. The protruding portions 256, asillustrated in FIG. 7, extend a length L1 beyond the shoulders 254.

The overall length of the bearing member 252, the length L1 of theprotruding portion 256, the size of the shoulders 254, and the width W1of the bearing member 252 can be chosen so as to cooperate withcorresponding components of the housing 250. For example, the parametersand characteristics of the bearing member 252 noted above can be chosensuch that the bearing member 252 can rest within the housing 250 so asto be trapped.

For example, the housing 250 can include a bearing member supportsurface 260 and end receivers 262. The arrangement and configuration ofthe end receivers 262 can be configured to cooperate with the shoulders254 and the projecting portions 256 so as to retain the bearing memberin an operational alignment during use. Optionally, the housing caninclude apertures 264 and end stops 266. In such a configuration, theapertures 264 can include lateral ends 270 which define stops for theshoulders 254. Additionally, the end stops 266 can define stops for theterminal ends of the protruding portions 256. Further, the position ofthe end stops 266 can be disposed so as to result in a close proximalspacing or contact with the terminal ends of the protruding portions256.

For example, as illustrated in FIG. 9, the bearing member 252, wheninstalled in the housing 250, can rest against the support surface 260of the housing 250. Each of the ends of the bearing member 252 canextend through the apertures 264 such that the terminal ends of theprotruding portions 256 lie in close proximity or in contact with thestops 266. Additionally, the shoulders 254 can rest against the stops270 formed at the lateral edges of the apertures 264. In thisconfiguration, the bearing member 252 can be “trapped” within thehousing 250, and thereby resist movement that may tend to shift thebearing member 252 out of the housing 250. Additionally, the bearingmember 252 can be installed into the housing without any tools. Thus,the connection between the bearing member 252 and the housing 250 can beconsidered a tool-less connection.

The size of the housing and the bearing member 252 can be configuredsuch that the inner surface of the bearing member 252 lies along aradius of curvature R1 that is close to, approximately the same, orslightly larger than the outer radius R2 of the torque tube 16. Thus,the torque tube 16 can pivot about its pivot axis A such that the outersurface of the torque tube 16 slides against the inner surface of thebearing member 252.

As shown in FIG. 9, the housing 250 and the bearing member 252 areconfigured so as to extend along the radius R1 over an arc of about180°. The terminal ends of the bearing member 252 flare away from theinner portion of the bearing 20 past the 180° of curvature. As such,with the bearing member 252 and housing 250 mounted to a top of a pier,a torque tube 16 can be lowered down onto the bearing 20 and intosliding engagement or sliding contact with the bearing member 252 withthe bearing member 252 and the housing 250 in a fully assembled state.In other words, the terminal ends of the bearing member 252 arepositioned such that at least a portion (e.g., the lower half) of thetorque tube 16 can pass between the terminal ends.

This can provide an important advantage in the installation process of asolar system. For example, as noted above, the torque tube 16 can bepremanufactured with many components mounted or fixed thereto withwelding and/or fasteners. This allows for high precision mounting andmanufacturing of such systems in a facility (“factory”) for providinghigh precision and high speed assembly. With such portions of the systemprefabricated, and in particular, braces and supports directly connectedto the torque tube 16, the torque tube 16 can be lowered onto anassembled bearing 20.

This manner of insulation is not possible using devices commonly knownas “roller bearings” which normally have to be slid over one end of acylindrical member such as a torque tube 16. Additionally, if thebearing 20 or any of its components need replacement, the torque tube 16could be supported just above its normal position during operation, anda replacement component such as a bearing member 252 can be installed.

It is not necessary that the bearing member 252 extend around the torquetube 16 for a complete 180°. Rather, in some embodiments, the housing250 and bearing member 252 can be configured to follow the radius ofcurvature R1 around about 100° around the torque tube 16. Along theselines, the housing 250 and the bearing member 252 can be configured toextend around any portion of the outer surface of the torque tube 16,such as, between 100° and 180° around the torque tube 16.

In the configuration illustrated in FIGS. 5-9, the bearing member 252 isloaded almost purely in compression, without any tension forces exertedthereon. This is because the ends of the bearing member 252 are notfixed relative to the housing 250. Rather, they can move relative to thehousing 250, to some extent.

FIG. 10 illustrates another embodiment of the bearing 20, and isidentified by the reference numeral 320. Components of the bearing 320can be similar or the same as those of the bearing 20 and have beenidentified with the same reference numerals, except that 100 has beenadded to the reference numerals used to identify components of thebearing 20.

With reference to FIG. 10, the bearing 320 can include a safety strap321 that can extend over the bearing 320 so as to prevent anyinadvertent movement of a torque tube 16 off of the bearing 320. Thesafety strap 321 can be made from any material, including, for example,but without limitation, sheet steel, aluminum, polyurethane, etc. Withreference to FIGS. 11-13, the housing 350 of the bearing 320 can includefasteners 372 that can be configured to engage with apertures 374disposed near the terminal ends of the bearing member 352.

As shown in FIG. 13, the bearing member 352 can be mounted to thehousing 350 in a manner similar to that described above with referenceto the bearing 20 and FIG. 9. However, in this embodiment, the apertures374 can align with the fasteners 372 so as to further secure theterminal ends of the bearing member 352 relative to the housing 350.

In such an embodiment, the bearing member can be loaded additionally intension due to the interaction between the fasteners 372 and theapertures 374. However, due to the other corresponding components of thebearing member 352 on the housing 350, such as the shoulders 354 andstops 370, it is not necessary for the fasteners 372 to be in the formof rivets, bolts, or other type of fastener for more permanently fixingthe bearing member 352. Rather, the fasteners 372 can be in the form ofpins sufficient to retain the bearing member 352 in place.

Further, the fasteners 372 can be provided with sufficient strength toprovide some load on the bearing member 352 in tension, during use. Forexample, the length of the bearing member 352 can be made sufficientlyshort such that the bearing member 352 does not lie against the surface360 of the housing 350 when the apertures 374 are engaged with thefasteners 372. Thus, when a torque tube 16 is lowered onto the bearingmember 352, the bearing member 352 can be stretched due to theinteraction of the apertures 374 with the fasteners 372 and the weightof the torque tube 16. Thus, the bearing member can be loaded both intension and compression during use in such an embodiment.

FIG. 14 illustrates yet another embodiment of the bearing assembly 20,identified by the reference numeral 420. Generally, the embodiment ofFIG. 14 is formed with two sets of the housings 250 and bearing members252 of the embodiment of FIGS. 5-9, arranged in an axially offset andopposed configuration. Thus, for example, the bearing 420 can be formedof an upper portion 480 and a lower portion 482, each of which can beformed by the combination of the housing 250 and bearing member 252 ofthe embodiments of FIGS. 5-8, except with the additional componentsnoted below. Thus, the various components of the upper and lowerportions 480, 482 will not be further described below.

In the orientation illustrated in FIG. 15, the lower portion 482, havinga generally u-shaped configuration, has an upwardly facing “bite”.Similarly, the upper portion 480 has a downwardly-facing “bite”.Additionally, this orientation can be described as the upper and lowerportions 480, 482, being axially offset (along the axis A) and opposedbecause their respective “bites” face toward each other.

With continued reference to FIGS. 14 and 15, each of the lower portionsand upper portions 482, 480 can include side mounting members 484. Themounting members 484 can be in the form of plates rigidly fixed orformed monolithically with the corresponding housings 450. In someembodiments, the mounting members 484 can include apertures 486.

With reference to FIG. 15, in some embodiments, the upper and lowerportions 480, 482 can be positioned such that the apertures 486 in themounting members 484 align with one another. In this configuration,fasteners 488 can be secured through the aligned apertures 484 forsecuring the upper portion 480 and the lower portion 482 to each other.Additionally, the apertures 486 in the mounting members 484 can bealigned such that the focal points F of the radiuses of the curvature ofeach of the inner surface of the bearing members 452. Normally, duringuse, the focus point F of the radius of curvature of the inner surfacesof the bearing members 452 will be aligned generally with the pivot axisA of the torque tube 16.

This type of configuration can provide a further benefit in someinstallations. For example, some solar systems can generate large liftforces on the torque tube 16 during wind events. Sustained winds cancreate continuous uplift forces on the torque tube 16 which must becounteracted to prevent the torque tubes 16 from lifting off of itsassociated piers. Thus, by using the upper portion 480 of the bearingassembly 420, the associated bearing member 452 of the upper portion 480can continue to provide reduced friction and wear from controlledpivoting of the torque tube 16. Additionally, when installing the torquetube 16, the torque tube can be lowered down onto the lower portion 482,then the upper portion 480 can be installed with the torque tube 16resting on the lower portion 482.

This type of configuration can be particularly useful where the winduplift forces, at a 20 mph horizontal east/west windflow are greaterthan the total weight supported by the piers 102 of the system. Such awind could be sufficient to lift the torque tubes off of theirrespective bearings and thus generate component wear friction against asafety strap, such as the safety strap 321 illustrated in FIG. 10. Forexample, some arrangement can generate substantial lift when pivotedtoward a “noon-angle” and subject to a 20 mph, horizontal wind. A netuplift force that can lift the torque tube 16 off of its associatedbearing can be expressed as when the ratio, defined by the combinedweight of the plurality of photovoltaic devices 14, which are pivotedtoward a noon sun angle and the weight of the torque tube 16 and all ofthe other equipment supported by the torque tube, divided by the liftgenerated by the photovoltaic devices 14 under a 20 mph transversehorizontal wind, is less than one

Some types of solar systems, such as the concentrated photovoltaicsystem illustrated schematically in FIG. 4, generally do not generatelarge uplift forces. For example, a system such as that illustrated inFIG. 4 under a sustained 20 mph horizontally directed east/west wind maynot result in an uplift force on the torque tube 16 greater than thetotal weight supported by the pier 102. Thus, those types of systems canbenefit from the reduced parts cost associated with the embodimentsillustrated in FIGS. 5-13, in which there is only one bearing memberextending around the lower side of the torque tube 16. Optionally, thesafety strap 321 (FIG. 10) can be used to prevent an inadvertentdislocation of the torque tube from the associated bearing, such as thatwhich may be generated by a large, transient wind gust.

As noted above, the simplified nature of the bearing members 252, 352,452, in some embodiments, can allow these bearing members to be“snapped” or otherwise installed to the respective housings withouttools. As such, the bearing members in the associated housings can beconsidered to form tool-less connections with each other. In someembodiments, the bearing members 252, 352, 452, can be made from a sheetmaterial having a thickness of about 0.125″. However, other thicknessescan also be used.

FIGS. 16-20 illustrate yet another embodiment of the bearing assembly20, identified by the reference numeral 520. As shown in FIG. 17, thesupport surface 560 can include, optionally, a crowned portion 582. Inthe illustrated embodiment, the crowned portion 582 is generally convexon the upper surface of the support surface 560; the side of the supportsurface 560 which supports and contacts the bearing member 552.

In the illustrated embodiment, due to the crowned configuration of thecrowned portion 582, the bearing member 552 can deform under the weightof a torque tube, such as the torque tube 16. Thus, although the bearingmember 552 may be made from a thin sheet like material, such as an ultrahigh molecular weight polyethylene material, such sheet material can bedistorted to follow the contour of the crowned portion 582, under theweight of a torque tube 16.

Optionally, a central portion of the bearing member 552 can be narrowedrelative to the terminal ends 556 of the bearing member 552. Forexample, in the illustrated embodiment, a central portion of the bearingmember 552 has a width W2 that is less than the width W1 at a portion ofthe bearing member 552 adjacent to the terminal ends 556.

The crowned portion 582 can be provided with any convex configuration.As such, housing 550 can better accommodate misalignments of the housing550 with the final position of a torque tube 16.

For example, as noted above, it is possible that after installation of apier 102 and the housing such as the housing 550, the support surface560 might not be exactly aligned or parallel with an outer surface ofthe torque tube 16 to be supported by the bearing assembly 520. Forexample, the support surface 560 might be inclined relative to the finalposition of the torque tube 16. FIG. 20 illustrates two possible finalpotential positions for the torque tube 16; an aligned, horizontalposition identified by dashed line and a misaligned, inclined positionidentified by a dot-chain line.

With such a crowned configuration, the crowned portion 582 can helpmaintain a larger contact patch between the outer surface of the torquetube 16 and the bearing member 520. For example, in the embodimentswhere the support surface is flat, such as the support surfaces 260,360, and 460, the contact patch between the outer surface of the torquetube 16 in the corresponding bearing member can be concentrated at theedge of the corresponding support surface when the torque tube 16 ismisaligned with the corresponding bearing 20, because those supportservices are flat. However, where the support surface, such as thesupport surface 560, includes a crowned portion 582, for example, at acenter or low point of the support surface 560, the crownedconfiguration can help provide a more continuous and therefore largercontact patch between the outer surface of the torque tube 16 and thebearing member. Such a configuration can help reduce the magnitude ofstress concentrations between the outer surface of the torque tube 16and the bearing member and thus reduce the speed of wearing of thebearing member.

In some embodiments, the crowned portion 582 of the support surface 560can be configured to follow a single radius of curvature R3 between itsforward and rear word axial edges 584, 586. However, other shapes canalso be used.

In some embodiments, the convex portion 582 can be sufficiently curvedsuch that a tangent line T extending from the forward axial edge 584extends at an angle C relative to a horizontal plane H. In someembodiments, the angle C can be about 7°. However, other angles can alsobe used.

With continued reference to the FIGS. 17-20, the housing 550 can be madefrom one or more portions. In the illustrated embodiment, the housing550 is made from two portions, 550A, 550 B, however, the housing 550 canbe made from any number of parts.

In the illustrated embodiment, the portions 550A, 550B have the sameshape and can be identical to one another. Each of the portions 550A,550B include stops 584 extending downwardly from a lower edge of thesupport surface 560. The stops 584 are positioned such that when the twoportions 550A, 550B are juxtaposed to one another, their respectiveoutward faces contact each other. As such, the stops 584 can be used tohelp align the portions 550A, 550B relative to each other.

In some embodiments, the portions 550A, 550B can be secured to eachother prior to being mounted to a pier 102. Optionally, the portions550A, 550B can be joined to the pier 102 and joined to each other at thetime of installation. In some embodiments, the stops 584 can alsoinclude a recess, notch, or aperture 586 which can be aligned with theaperture 221 (FIG. 6). As such, the recess 586 can also assist inaligning the portions 550A, 550B with the desired location.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A sun-tracking photovoltaic solar collectorarray, comprising: a plurality of photovoltaic devices; a supportassembly supporting the photovoltaic devices so as to be pivotable abouta pivot axis, the support assembly comprising: at least a first pivotsupporting the plurality of photovoltaic modules; at least a firstbearing supporting the first pivot so as to be pivotable about the pivotaxis; and at least one pier supporting the bearing at a position above asupport surface, the bearing comprising at least a first reducedfriction member extending around a first arc of at least about 100degrees about the first pivot, the first reduced friction membercomprising a first end, a second end, and a central portion, the firstand second ends being spaced apart sufficiently to allow at least aportion of the first pivot to pass between the first and second ends.